Table 2.

Characteristics of studies included in the meta-analysis

Study characteristics						T characteristics			Reported outcomes
Studya	Article	Population	Comparisonb	Group	N	Type/Mode	Dose	Duration (wks)	Serum T elevation group	FFM methodc	FFM elevation group	Physical performance metric(s)
1	Bhasin et al., 1996 [24]	YNG (normal body weight, 19-40 y)	1	T + E	11	Enanthate intramuscular injection	600 mg/wk	10	THI	UW	FFMHI	Lower body strength,
				P + E	9
			2	T	10				THI		FFMHI	Upper body strength
				P	10
2	Bhasin et al., 2000 [25]	DIS (HIV, weight loss, low T, 18-50 y)	3	T + E	11	Enanthate intramuscular injection	100 mg/wk	16	TLO	DEXA	FFMLO	Lower body strength,e
				P + E	11
			4	T	15				TLO		FFMLO	Upper body strengthe
				P	12
3	Casaburi et al., 2004 [32]	DIS (COPD, low T, 55-80 y)	5 6	T + E P + E	11 12	Enanthate intramuscular injection	100 mg/wkd	10	TLO TLO	DEXA	FFMLO FFMHI	Lower body strength,
				T P	12 12							Lower body muscular endurance,
												Lower body power,
												Aerobic endurancee
4	Clague et al., 1999 [33]	OLD (low T, >60 y)	7	T P	7 7	Enanthate intramuscular injection	200 mg/2 wk	12	THI	BIA	FFMLO	Lower body strengthe,
												Lower body power,
												Handgrip,
												Functional test
5	Dillon et al., 2018 [26]	YNG (head-down bed rest, 24-55 y)	8	T + E	8	Enanthate intramuscular injection	100 mg/wk, 2 wk off between	10	TLO	DEXA	FFMHI	Lower body strengthe
				P + E	8
6	dos Santos et al., 2016 [34]	DIS (CHF, low T, 18-65 y)	9	T + E P + E	8 11	Undecanoate intramuscular injection	1000 mg/ onced	16	THI	DEXA	FFMHI	Lower body power,
												Aerobic endurance
7	Emmelot-Vonk et al., 2008 [35]	OLD (low T, 60-80 y)	10	T P	104 103	Undecanoate oral pills	80 mg/2× day	24	TLO	DEXA	FFMLO	Lower body strength,
												Handgrip,
												Functional test
8	Giannoulis et al., 2006 [36]	OLD (low T, 65-80 y)	11	T P	21 16	Transdermal patch	5 mg/day	24	TLO	DEXA	FFMHI	Lower body strengthe,,
												Aerobic endurance,
												Handgrip
9	Grinspoon et al., 1998 [37]	DIS (HIV, weight loss, low T, 18-49 y)	12	T	22	Enanthate intramuscular injection	300 mg/3 wk	24	TLO	DEXA	FFMHI	Functional teste
				P	19
10	Kenny et al., 2001 [27]	OLD (low T, >65 y)	13	T	24	Transdermal patch	5 mg/day	52	TLO	DEXA	FFMLO	Lower body strength
				P	20
11	Kenny et al., 2010 [38]	OLD (low T, low BMD/frailty, >60 y)	14	T P	53 46	Transdermal gel	5 mg/day	52	TLO	DEXA	FFMLO	Lower body strength,
												Lower body power,
												Handgrip,
												Functional teste
12	Knapp et al., 2008 [39]	DIS (HIV, weight loss, low T, 18-60 y)	15	T P	21 27	Enanthate intramuscular injection	300 mg/wk	16	THI	DEXA	FFMLO	Lower body strength,
												Lower body muscular endurance,
												Lower body power,
												Functional teste
13	Page et al., 2005 [40]	OLD (low T, >65 y)	16	T	17	Enanthate intramuscular injection	200 mg/2 wkd	144	TLO	DEXA	FFMHI	Handgrip,
												Functional test
				P	18
14	Pasiakos et al., 2019 [41]	YNG (military training, 18-39 y)	17	T P	24 26	Enanthate intramuscular injection	200 mg/wk	4	THI	DEXA	FFMHI	Lower body strengthe,
												Lower body muscular endurance
15	Sheffield-Moore et al., 2011 [28]	OLD (low T, 60-85 y)	18	T	8	Enanthate intramuscular injection	100 mg/wk	20	THI	DEXA	FFMHI	Lower body strengthe,
				P	8
			19	T	8		100 mg/8 wk		THI		FFMHI	Upper body strengthe,
				P	8
16	Snyder et al., 1999 [42]	OLD (low T, >65 y)	20	T P	50 46	Transdermal patch	6 mg/dayd	144	THI	DEXA	FFMLO	Lower body strengthe,
												Handgrip,
												Functional test
17	Srinivas-Shankar et al., 2010 [43]	OLD (frail, low T, >65 y)	21	T P	130 132	Transdermal gel	25–75 mg/dayd	24	~ THI	DEXA	FFMLO	Lower body strengthe,
												Handgrip,
												Functional teste
18	Travison et al., 2011 [44]	OLD (mobility limitation, low T, >65 y)	22	T	69 69	Transdermal gel	50–150 mg/dayd,	24	THI	DEXA	FFMLO	Lower body strength,
												Upper body strength,
												Lower body power,
												Handgrip,
												Functional teste
19	Wittert et al., 2003 [29]	OLD (low T, >60 y)	23	T	33	Undecanoate oral pills	40–80 mg/2× dayd,	52	TLO	DEXA	FFMLO	Lower body strengthe,
				P	25							Handgrip
20	Zachwieja et al., 1999 [30]	YNG (head-down bed rest, 31-47 y)	24	T P	6 4	Enanthate intramuscular injection	75 mg/day for 3 days, 200 mg/wk after	4	THI	DEXA	FFMHI	Lower body strengthe,
												Upper body strengthe

BIA, bioelectrical impedance analysis; BMD, bone mineral density; CHF, chronic heart failure; COPD, chronic obstructive pulmonary disease; DEXA, dual-energy X-ray absorptiometry; DIS, “Diseased males” subgroup; FFM, fat-free mass; FFM_HI, treatment group experienced higher elevations in fat-free mass than the median of all groups; FFM_LO, treatment group experienced lower elevations in fat-free mass than the median of all groups; HIV, human immunodeficiency virus; LBM, lean body mass; OLD, “Older males” subgroup; P, placebo; P + E, placebo and exercise training; T, testosterone; T + E, testosterone and exercise training; T_HI, Treatment group experienced higher elevations in serum testosterone concentrations than the median of all groups; T_LO, treatment group experienced lower elevations in serum testosterone concentrations than the median of all groups; UW, underwater weighing; YNG, “Younger males” subgroup.

^aIndicates individual manuscripts identified for the meta-analysis.

^bIndicates each comparison extracted from individual manuscripts; each comparison was treated as a separate study.

^cDenotes methods to assess FFM. When multiple methods were used in the investigation, DEXA data was preferentially used in analysis.

^dIndicates that testosterone administration dosage alterations may have occurred in certain subjects.

^eIndicates that multiple tests of this subgroup were assessed and each was analyzed separately in current study.